U.S. patent application number 10/921511 was filed with the patent office on 2005-01-27 for method for making electronic devices including silicon and ltcc and devices produced thereby.
This patent application is currently assigned to HARRIS CORPORATION. Invention is credited to Gamlen, Carol, Newton, Charles M., O'Dowd, Betty, Pike, Randy T., Rumpf, Raymond C..
Application Number | 20050019986 10/921511 |
Document ID | / |
Family ID | 24982035 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050019986 |
Kind Code |
A1 |
Pike, Randy T. ; et
al. |
January 27, 2005 |
Method for making electronic devices including silicon and LTCC and
devices produced thereby
Abstract
A method for making an electronic device includes positioning
first and second members so that opposing surfaces thereof are in
contact with one another, the first member comprising silicon and
the second member comprising a low temperature co-fired ceramic
(LTCC) material. The method further includes anodically bonding
together the opposing surfaces of the first and second members to
form a hermetic seal therebetween. The anodic bonding provides a
secure and strong bond between the members without using adhesive.
The method may further include forming at least one cooling
structure in at least one of the first and second members. The
least one cooling structure may comprise at least one first
micro-fluidic cooling structure in the first member, and at least
one second micro-fluidic cooling structure in the second member
aligned with the at least one first micro-fluidic cooling
structure.
Inventors: |
Pike, Randy T.; (Indian
Harbour Beach, FL) ; Newton, Charles M.; (South East
Palm Bay, FL) ; Gamlen, Carol; (Melbourne, FL)
; Rumpf, Raymond C.; (Melbourne, FL) ; O'Dowd,
Betty; (Melbourne, FL) |
Correspondence
Address: |
CHRISTOPHER F. REGAN
ALLEN, DYER, DOPPELT, MILBRATH & GILCHRIST, P.A.
Post Office Box 3791
Orlando
FL
32802-3791
US
|
Assignee: |
HARRIS CORPORATION
|
Family ID: |
24982035 |
Appl. No.: |
10/921511 |
Filed: |
August 19, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10921511 |
Aug 19, 2004 |
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09741754 |
Dec 19, 2000 |
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6809424 |
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Current U.S.
Class: |
438/118 ;
257/E23.088; 257/E23.098; 257/E23.106 |
Current CPC
Class: |
H01L 23/3735 20130101;
H01L 2924/15151 20130101; H01L 21/4882 20130101; H01L 2224/83894
20130101; H01L 2924/15787 20130101; H01L 2924/19043 20130101; H01L
2924/01033 20130101; H01L 23/427 20130101; H01L 2924/15311
20130101; H01L 23/473 20130101; H01L 2924/00014 20130101; H01L
2924/1305 20130101; H01L 2924/1532 20130101; H01L 24/48 20130101;
H01L 2924/09701 20130101; H01L 2924/19041 20130101; H01L 2924/00015
20130101; H01L 2924/01057 20130101; H01L 2924/13055 20130101; H01L
21/4857 20130101; H01L 2224/48091 20130101; H01L 2924/01023
20130101; H01L 2924/1517 20130101; H01L 2224/48227 20130101; H01L
2924/15153 20130101; H01L 2924/01027 20130101; H01L 2924/14
20130101; H01L 24/31 20130101; H01L 2924/01006 20130101; H01L
2224/48091 20130101; H01L 2924/00014 20130101; H01L 2924/1305
20130101; H01L 2924/00 20130101; H01L 2924/00015 20130101; H01L
2224/45099 20130101; H01L 2924/00015 20130101; H01L 2224/85399
20130101; H01L 2924/00015 20130101; H01L 2224/05599 20130101; H01L
2924/00014 20130101; H01L 2224/45099 20130101; H01L 2924/00014
20130101; H01L 2224/45015 20130101; H01L 2924/207 20130101 |
Class at
Publication: |
438/118 |
International
Class: |
H01L 021/44; H01L
021/48; H01L 021/50 |
Claims
1. A method for making an electronic device comprising: positioning
first and second members so that opposing surfaces thereof are in
contact with one another, the first member comprising silicon and
the second member comprising a low temperature co-fired ceramic
(LTCC) material; and anodically bonding together the opposing
surfaces of the first and second members to form a hermetic seal
therebetween.
2. A method according to claim 1 wherein said first and second
members have substantially planar major opposing surfaces.
3. A method according to claim 1 wherein anodically bonding
comprises applying a voltage across the first and second
members.
4. A method according to claim 3 wherein anodically bonding further
comprises applying pressure to the opposing surfaces of the first
and second members.
5. A method according to claim 4 wherein anodically bonding further
comprises heating the first and second members.
6. A method according to claim 1 further comprising cleaning the
opposing surfaces of the first and second members prior to
anodically bonding.
7. A method according to claim 1 further comprising forming at
least one cooling structure in at least one of the first and second
members.
8. A method according to claim 7 wherein the at least one cooling
structure comprises at least one micro-fluidic cooling
structure.
9. A method according to claim 7 further comprising positioning at
least one integrated circuit adjacent the at least one cooling
structure.
10. A method according to claim 9 wherein the at least one
integrated circuit comprises electrical connections; and wherein
the second member carries external electrical connections connected
to the electrical connections of the at least one integrated
circuit.
11. A method according to claim 1 wherein anodically bonding
comprises applying a voltage in a range of about 500 to 1000 volts
across the first and second members.
12. A method according to claim 1 wherein anodically bonding
comprises applying pressure in a range of about 1 to 20 psi to the
opposing surfaces of the first and second members.
13. A method according to claim 1 wherein anodically bonding
comprises heating the first and second members to a temperature in
a range of about 100 to 150.degree. C.
14. A method for making an electronic device comprising:
positioning first and second members so that opposing generally
planar major surfaces thereof are in contact with one another, the
first member comprising silicon and the second member comprising a
low temperature co-fired ceramic (LTCC) material, the first member
also having at least one first micro-fluidic structure and the
second member also having at least one second micro-fluidic cooling
structure aligned with the at least one first micro-fluidic cooling
structure; and anodically bonding together the opposing generally
planar major surfaces of the first and second members to form a
hermetic seal therebetween.
15. A method according to claim 14 wherein anodically bonding
comprises applying a voltage across the first and second
members.
16. A method according to claim 15 wherein anodically bonding
further comprises applying pressure to the opposing surfaces of the
first and second members.
17. A method according to claim 16 wherein anodically bonding
further comprises heating the first and second members.
18. A method according to claim 14 further comprising cleaning the
opposing surfaces of the first and second members prior to
anodically bonding.
19. A method according to claim 14 further comprising positioning
at least one integrated circuit adjacent the at least one first
micro-fluidic cooling structure.
20. A method according to claim 19 wherein the at least one
integrated circuit comprises electrical connections; and wherein
the second member carries external electrical connections connected
to the electrical connections of the at least one integrated
circuit.
21-34. (canceled).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of electronic
devices and manufacturing methods, and, more particularly, to
methods for making and devices such as including packaged
integrated circuits.
BACKGROUND OF THE INVENTION
[0002] Integrated circuits are widely used in many types of
electronic equipment. An integrated circuit may include a silicon
substrate in which a number of active devices, such as transistors,
etc., are formed. It is also typically required to support one or
more such integrated circuits in a package that provides protection
and permits external electrical connection.
[0003] As the density of active devices on typical integrated
circuits has increased, dissipation of the heat generated has
become increasing more important. Designers have developed cooling
techniques for integrated circuits based on micro-electromechanical
(MEMs) technology.
[0004] For example, as shown in FIG. 1, a prior art electronic
device 10 includes a package 11 including a first member 12
comprising silicon, and a second member 14 comprising a low
temperature co-fied ceramic (LTCC) material. The first member 12
may include several stacked silicon substrates 12a, 12b having
various components of a micro-fluidic cooler formed therein. For
example, as shown in the illustrated embodiment, an evaporator 16
and condenser 17 may be provided and interconnected via one or more
micro-fluidic channels or passageways 21 formed between the silicon
substrates 12a, 12b. One or more MEMs pumps, not shown, may
circulate the cooling fluid.
[0005] The second member 14 may also include several LTCC layers
14a, 14b laminated together as shown in the illustrated embodiment.
The second member 14 also illustratively carries an integrated
circuit 22, such as an insulated gate bipolar transistor (IGBT) or
other integrated circuit that may typically generate substantial
waste heat. The second member 14 also includes external connections
23 which are connected to the electrical connections 24 of the
integrated circuit 22 via the illustrated wires 25.
[0006] As shown in the enlarged view of FIG. 2, the integrated
circuit 22 is carried by a receiving recess 27 in the second member
14. A series of micro-fluidic passageways 30 may be provided
through the LTCC member 14 adjacent the integrated circuit 22 to
deliver cooling fluid thereto.
[0007] Typically, the LTCC member 14 and the silicon member 12 are
adhesively joined together as schematically illustrated by the
adhesive layer 31. Thermoplastic and/or thermosetting adhesives are
commonly used. Metal layers may also be used. Unfortunately, the
adhesive layer 31 has a number of shortcomings. The adhesive layer
31 may not typically provide a hermetic seal at the interface
between the silicon and LTCC, thus, cooling fluid may be lost. In
addition, the adhesive layer 31 may also provide yet another layer
through which the heat must pass. Of course, it may be difficult to
provide an adhesive layer 31 which is uniform and which does not
protrude into the interface or otherwise block or restrict the flow
of cooling fluid. In other words, such an adhesive layer 31
unfortunately provides only non-hermetic and non-uniform bonding
the members.
[0008] U.S. Pat. No. 5,443,890 to Ohman discloses a leakage
resistant seal for a micro-fluidic channel formed between two
adjacent members. A sealing groove is provided and filled with a
fluid sealing material which is compressed against adjacent surface
portions of the opposing member. The provision for such a sealing
structure requires additional manufacturing steps and may not be
suitable for many applications.
SUMMARY OF THE INVENTION
[0009] In view of the foregoing background, it is therefore an
object of the invention to provide a method and associated
electronic device wherein LTCC and silicon members are bonded
together to form a hermetic seal with uniform bonding.
[0010] This and other objects, features and advantages in
accordance with the present invention are provided by a method for
making an electronic device comprising positioning first and second
members so that opposing surfaces thereof are in contact with one
another, the first member comprising silicon and the second member
comprising a low temperature co-fired ceramic (LTCC) material. The
method also includes anodically bonding together the opposing
surfaces of the first and second members to form a hermetic seal
therebetween. The anodic bonding provides a secure and uniform bond
between the members.
[0011] The first and second members may have substantially planar
major opposing surfaces. The anodic bonding provides a uniform bond
across these surfaces to reduce possible stress effects which may
otherwise occur due to the difference in thermal coefficients of
expansion of the two different materials.
[0012] Anodically bonding may comprise applying a voltage across
the first and second members, applying pressure to the opposing
surfaces of the first and second members, and/or heating the first
and second members. The method may also include cleaning the
opposing surfaces of the first and second members prior to
anodically bonding the members.
[0013] The method may further include forming at least one cooling
structure in at least one of the first and second members. More
particularly, the least one cooling structure may comprise at least
one first micro-fluidic cooling structure in the first member, and
at least one second micro-fluidic cooling structure in the second
member aligned with the at least one first micro-fluidic cooling
structure. The at least one first micro-fluidic cooling structure
may comprise an evaporator and the at least one second
micro-fluidic cooling structure may comprise at least one
micro-fluidic passageway. Anodic bonding permits a hermetic seal
between the two members, and significantly reduces or eliminates
the loss of cooling fluid at the interface between the two members
which could otherwise occur.
[0014] The method may also include positioning at least one
integrated circuit adjacent the at least one cooling structure,
such as adjacent the at least one micro-fluidic cooling passageway
in the second member. The at least one integrated circuit may
comprise electrical connections, and the second member may carry
external electrical connections connected to the electrical
connections of the at least one integrated circuit.
[0015] For typical electronic devices, the anodically bonding may
comprise applying a voltage in a range of about 500 to 1000 volts
across the first and second members. Similarly, the anodically
bonding may comprise applying pressure in a range of about 1 to 20
psi to the opposing surfaces of the first and second members.
Continuing along these lines, the anodically bonding may comprise
heating the first and second members to a temperature in a range of
about 100 to 150.degree. C.
[0016] Another aspect of the invention relates to an electronic
device, such as a multi-chip module (MCM) or other similar packaged
integrated circuit, for example. The electronic device may comprise
a first member comprising silicon, and a second member comprising a
low temperature co-fired ceramic (LTCC) material. Moreover, the
first and second members have opposing surfaces thereof anodically
bonded together to form a hermetic seal therebetween. The first and
second members may have opposing generally planar major opposing
surfaces, for example.
[0017] At least one of the first and second members may comprise at
least one cooling structure. For example, the first member may
comprise at least one first micro-fluidic cooling structure
therein, such as an evaporator. In addition, the second member may
further comprise at least one second micro-fluidic cooling
structure aligned with the at least one first micro-fluidic cooling
structure of the first member. For example, the at least one second
micro-fluidic cooling structure may comprise at least one
micro-fluidic passageway.
[0018] The electronic device may also include at least one
integrated circuit adjacent the at least one second micro-fluidic
cooling structure of the second member. The at least one integrated
circuit may also comprise electrical connections. Accordingly, the
second member may comprise external electrical connections
connected to the electrical connections of the at least one
integrated circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic cross-sectional view of an electronic
device according to the prior art.
[0020] FIG. 2 is a greatly enlarged view of a portion of the
electronic device as shown in FIG. 1.
[0021] FIG. 3 is a schematic cross-sectional view of an electronic
device in accordance with the present invention.
[0022] FIG. 4 is a greatly enlarged portion of the electronic
device as shown in FIG. 3.
[0023] FIG. 5 is a schematic diagram of the electronic device as
shown in FIG. 3 being made in an apparatus in accordance with the
invention.
[0024] FIG. 6 is a schematic diagram of the anodic bond interface
as in the electronic device shown in FIG. 3.
[0025] FIG. 7 is a flowchart illustrating the method in accordance
with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the illustrated embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those skilled in the art. Like numbers
refer to like elements throughout.
[0027] Referring now initially to FIGS. 3-7 the electronic device
and method for making the device in accordance with the invention
are now described. In particular, as shown in FIGS. 3 and 4, an
illustrated embodiment of an electronic device 110 in accordance
with the invention is shown. The electronic device 110 differs from
the prior art device shown in FIGS. 1 and 2 in that the
conventional adhesive layer 31 is replaced by an anodically bonded
interface 135 as will be described in greater detail herein.
[0028] The electronic device 110 illustratively mounts a single
integrated circuit 122 in the package 111 although those of skill
in the art will recognize that the invention is also applicable to
other electronic devices as well. For example, the electronic
device may also be an MCM, or other similar device including one or
more integrated circuits 122 contained in a similar mounting
package. The electronic device 110 illustratively includes a first
member 112 comprising silicon, and a second member 114 comprising a
low temperature co-fired ceramic (LTCC) material. The first and
second members 112, 114 have opposing surfaces thereof anodically
bonded together to form a hermetic seal at the interface 135
therebetween.
[0029] As shown in the illustrated embodiment, the first and second
members 112, 114 have opposing generally planar major opposing
surfaces being anodically bonded together. At least one of the
first and second members 112, 114 may comprise at least one cooling
structure therein as will be appreciated by those skilled in the
art. For example, as shown in the illustrated electronic device
110, the first member 112 includes at least one first micro-fluidic
cooling structure therein, such as the illustrated evaporator
116.
[0030] The second member 114 may include at least one second
micro-fluidic cooling structure aligned with the at least one first
micro-fluidic cooling structure of the first member 112. For
example, and as shown in the illustrated embodiment of the
electronic device 110, the at least one second micro-fluidic
cooling structure may comprise at least one micro-fluidic
passageway 130.
[0031] The electronic device 110 also illustratively includes an
integrated circuit 122 adjacent the micro-fluidic passageways 130
of the second member 114. Of course, in other embodiments, more
than one integrated circuit may be mounted within the package 111.
In addition, an optical/electronic device may also be mounted and
cooled as described herein as will be appreciated by those skilled
in the art. The integrated circuit 122 also illustratively includes
electrical connections 124 which are brought out to the external
electrical connections 123 using conventional techniques as will be
appreciated by those skilled in the art.
[0032] As will also be appreciated by those skilled in the art, in
other embodiments of the invention, the integrated circuit 122 may
include a back contact layer, not shown, which is also connected to
an external electrical connector carried by the second member. In
addition, the integrated circuit 122 may be mounted using flip chip
bonding techniques in other embodiments.
[0033] The other elements of the illustrated electronic device 110
of the invention are indicated with reference numerals incremented
by one hundred as compared to the similar elements of the
electronic device shown in FIGS. 1 and 2. Accordingly, these common
elements need no further discussion herein.
[0034] Referring now more particularly to FIGS. 5-7, method aspects
of the invention are now described in greater detail. The method is
for making an electronic device 110, such as described above. As
seen in the flowchart of FIG. 7, from the start (Block 150) the
method may include cleaning and preparation of the opposing
surfaces of the first and second members 112, 114 at Block 152.
Preparation may include polishing or other techniques to ensure
that the surface roughness of each opposing surface is within a
desired range.
[0035] At Block 154 the method includes positioning first and
second members 112, 114 so that opposing surfaces thereof are in
contact with one another. As described above, the first member 112
comprises silicon and the second member 114 comprises an LTCC
material. At Block 156 the opposing surfaces of the first and
second members 112, 114 are anodically bonding together.
[0036] Referring now briefly to the schematically illustrated
apparatus 140 of FIG. 5 an embodiment of anodic bonding is further
described. The first and second members 112, 114 may be aligned
between the top electrode 142 and the bottom electrode 141 of the
apparatus 140. The bottom electrode 141 is also carried by a heated
support 144. A voltage source 143 is connected to the top and
bottom electrodes 142, 141. The apparatus 140 can provide the
necessary voltage, pressure and temperature ranges for efficient
anodic bonding of the first and second members 112, 114.
[0037] For typical electronic devices such as the illustrated
electronic device 110 or MCMs, for example, the voltage source 143
may apply a voltage in a range of about 500 to 1000 volts across
the first and second members 112, 114. Similarly, the apparatus may
also apply a force such that the pressure between the opposing
surfaces is in a range of about 1 to 20 psi. Additionally, the
heated support may heat the first and second members 112, 114 to a
temperature in a range of about 100 to 150.degree. C. Of course,
other voltages, pressures and temperatures are contemplated by the
invention and may be used for other devices as will be appreciated
by those skilled in the art. After the anodic bonding (Block 156),
the bonded first and second members 112, 114 may be cleaned and
further processed before stopping (Block 160).
[0038] As described above, the first and second members 112, 114
may have substantially planar major opposing surfaces, so that
anodic bonding provides a uniform bond across these surfaces to
reduce possible stress effects which may otherwise occur due to the
difference in thermal coefficients of expansion of the two
different materials. The anodic bonding provides a secure and
uniform hermetic seal between the members 112, 114 and while
overcoming the disadvantages described above resulting from using
an adhesive.
[0039] The method may further include forming at least one cooling
structure in at least one of the first and second members 112, 114.
These may be formed before or after anodic bonding, or they may be
formed both before and after anodic bonding. The method may also
include positioning at least one integrated circuit 122 adjacent
the at least one cooling structure, such as adjacent the at least
one micro-fluidic cooling passageways 130 in the second or LTCC
member 114.
[0040] Anodic bonding advantageously provides a hermetic seal
between the two members, and significantly reduces or eliminates
the loss of cooling fluid at the interface between the two members
which could otherwise occur. It is believed without applicants
wishing to bound thereto that the anodic bonding causes a
coordinate covalent matrix to form at the interface 135 between the
first and second members 112, 114 as perhaps best shown in the
schematic view of FIG. 6.
[0041] Many modifications and other embodiments of the invention
will come to the mind of one skilled in the art having the benefit
of the teachings presented in the foregoing descriptions and the
associated drawings. Accordingly, it is understood that the
invention is not to be limited to the embodiments disclosed, and
that other modifications and embodiments are intended to be
included within the spirit and scope of the appended claims.
* * * * *